Mars, the Evocative Garbage

Opportunity’s size dominates crater. "This is a picture of the vehicle," said Malin, referring to a bright spot. "One thing to note is how big it is relative to the crater. It fills the size of the crater." Click image for larger view.Credit:NASA/JPL/ MSSS

When the signals in late January came to Earth from crippled Spirit software, its computer’s clocktime indicated it was the year 2053. Like a moment of time travel lifted from a science fiction novel, the momentary glitch suggested a futuristic way to envision how someday one might encounter what scientists once left behind back then, in the year 2004.

The debris list for a mobile laboratory is impressive: one parachute, heatshield, back shell and base petal. As the laboratory moves out across the martian plains, the golf-cart-sized rover occasionally encounters these remnants on the horizon. The banner image released today from the Spirit rover’s panorama shows the heatshield perched on the edge of its nearby crater called Bonneville. At the Opportunity site on the other side of Mars, the debris field similarly is located within about a half-kilometer radius.

Presenting remarkable orbital images that document the various stages of the mission, Mike Malin who designed and operates the Mars Orbital Camera first highlighted various pieces of hardware now visible on the surface. "We see where the heat shield hit, the plume from when the retro rocket fired. Finally where the back shell and parachute hit."

As JPL Center Director, Dr. Charles Elachi, pointed out on the first night of the Spirit rover’s landing, each day is a new landing if the rover can roam around to investigate new landscapes. The martian laboratories are on wheels. While sometime at the end of 2004, the rovers themselves will become inoperable and join this museum of surface hardware, until then the ability to find the various important stages of their descent and operation gives insight into what is unique about this generation of explorers: their mobile cameras.

Correlating surface debris with distance seen from orbit. Click image for larger view. The orbital view shows Opportunity’s bright parachute seen from hundreds of miles overhead at 1.5 m pixel resolution, while the rover’s panoramic camera identifies the debris on the flat martian plains.Credit:NASA/JPL/ Cornell/MSSS

While previous orbital views have identified Viking and Pathfinder shadows on the surface, there is no similar ability to see anything from the surface.

Malin pointed out that this combination of orbital and surface imagery was important to locating the rovers’ coordinates. "The navigation camera showed a view of the backshell and parachute from the lander. The pancam [on the rover] has taken a picture of this, as it is quite an evocative image. From the rover, outside the low rim of the crater, it is quite a pretty picture, showing over this vast, flat surface, there is the hardware we have littered the surface with."

When asked to speculate on when both rovers might become part of the Mars museum of space debris, mission manager Jennifer Trosper said the limits are both seasonal and weather related. "The dust accumulation on the solar panels is something that will take lifetime out of the mission. The design lifetime of 90-plus days is based on the Pathfinder dust deposit rate. When it starts getting colder, we need more survival heating at night. It doesn’t limit the life, we just need to save more energy to heat the electronics box and mini-TES, which is actually more exposed [to cold]. The dust deposition and the temperatures [those are the limits] over the course of time."

Current plans suggest that the mission will extend well beyond its initial success criterion of 90-days, perhaps as far as September. Mission manager, Matt Wallace, concluded that both rovers were healthy. "We try to keep our finger on the pulse of vehicle health, looking for signals or markers of subtle changes and trends. Except for environmental changes (power, thermal, optical opacity and dust accumulation), there is no wear and tear on subsystems."

The idea that this space debris one day might become future ‘messages in a bottle’ has long led to attaching various messages to address a future discovering party. Bill Nye, who spearheaded the message format on the current Mars’ Sundials, told Astrobiology Magazine about his reasoning. "As a student of Carl Sagan’s, a Planetary Society Board Member, I came of age during the Voyager missions. I was in the lecture on during the days, when Professor Sagan asked the class which songs we thought were worthy of being sent out of our Solar System, messages in bottles to be cast into the Cosmic Ocean. These were whimsical in a sense, almost silly, self-delusional perhaps. The chance that they will ever be found is almost unimaginably remote. But, it is also a notion that fills us with wonder and hope. The idea is irresistible– a message from humankind for all time."

On both rovers, Nye’s sundial inscription for posterity reads: "People launched this spacecraft from Earth in our year 2003. It arrived on Mars in 2004. We built its instruments to study the martian environment and to look for signs of water and life. We used this post and these patterns to adjust our cameras and as a sundial to reckon the passage of time. The drawings and words represent the people of Earth. We sent this craft in peace to learn about Mars’ past and about our future. To those who visit here, we wish a safe journey and the joy of discovery."